Did you know arm span ( also known as wingspan or reach ) is approximately equal to height?
How to calculate arm span
We tested this out against a wall using chalk to mark reach and then standing next to the wall to see if it matched height. You should measure from fingertip to fingertip and not have a flat hand as in this photo.
We found my 6 year old’s arm span did equal his height and my 4 year old was a little taller than hers.
What is ape index?
Ape index is the ratio of arm span relative to their height. So my little boy had an ape index of 1.
A arm span greater than height is thought to be advantageous in some sports such as swimming, as longer arms may give greater propulsion. A shorter arm span is useful for weight lifters as they don’t have to lift the weight as high.
How to calculate ape index
Ape Index – Method 1
Wingspan / Height
If ape index is greater than 1, wingspan is greater than height. If ape index is less than one height is greater than wingspan.
Ape Index – Method 2
Wingspan – Height
Ape index calculated this way is either a positive or negative number.
Can you work out your ape index or arm span?
Download the instructions
More human body science ideas
Can you work out how many feet tall you are too?
Or , for little ones try some of these great preschool science ideas.